Starch biosynthesis is important for plant development and is a critical factor in crop quality and nutrition. As a complex metabolic pathway, the regulation of starch biosynthesis is still poorly ...understood. We here present the identification of candidate regulators for starch biosynthesis by gene coexpression analysis in rice (Oryza sativa). Starch synthesis genes can be grouped into type I (in seeds; sink tissues) and type II (in vegetative tissues; source tissues), and 307 and 621 coexpressed genes are putatively involved in the regulation of starch biosynthesis in rice seeds and vegetative tissues, respectively. Among these genes, Rice Starch Regulator1 (RSR1), an APETALA2/ethylene-responsive element binding protein family transcription factor, was found to negatively regulate the expression of type I starch synthesis genes, and RSR1 deficiency results in the enhanced expression of starch synthesis genes in seeds. Seeds of the knockout mutant rsr1 consistently show the increased amylose content and altered fine structure of amylopectin and consequently form the round and loosely packed starch granules, resulting in decreased gelatinization temperature. In addition, rsr1 mutants have a larger seed size and increased seed mass and yield. In contrast, RSR1 overexpression suppresses the expression of starch synthesis genes, resulting in altered amylopectin structure and increased gelatinization temperature. Interestingly, a decreased proportion of A chains in rsr1 results in abnormal starch granules but reduced gelatinization temperature, whereas an increased proportion of A chains in RSR1-overexpressing plants leads to higher gelatinization temperatures, which is novel and different from previous reports, further indicating the complicated regulation of starch synthesis and determination of the physicochemical properties of starch. These results demonstrate the potential of coexpression analysis for studying rice starch biosynthesis and the regulation of a complex metabolic pathway and provide informative clues, including the characterization of RSR1, to facilitate the improvement of rice quality and nutrition.
Abstract
Photocatalytic formation of hydrocarbons using solar energy via artificial photosynthesis is a highly desirable renewable-energy source for replacing conventional fossil fuels. Using an
l
...-cysteine-based hydrothermal process, here we synthesize a carbon-doped SnS
2
(SnS
2
-C) metal dichalcogenide nanostructure, which exhibits a highly active and selective photocatalytic conversion of CO
2
to hydrocarbons under visible-light. The interstitial carbon doping induced microstrain in the SnS
2
lattice, resulting in different photophysical properties as compared with undoped SnS
2
. This SnS
2
-C photocatalyst significantly enhances the CO
2
reduction activity under visible light, attaining a photochemical quantum efficiency of above 0.7%. The SnS
2
-C photocatalyst represents an important contribution towards high quantum efficiency artificial photosynthesis based on gas phase photocatalytic CO
2
reduction under visible light, where the in situ carbon-doped SnS
2
nanostructure improves the stability and the light harvesting and charge separation efficiency, and significantly enhances the photocatalytic activity.
Some New Constructions of Quantum MDS Codes Fang, Weijun; Fu, Fang-Wei
IEEE transactions on information theory,
2019-Dec., 2019-12-00, Volume:
65, Issue:
12
Journal Article
Peer reviewed
Open access
It is an important task to construct quantum maximum-distance-separable (MDS) codes with good parameters. In the present paper, we provide six new classes of <inline-formula> <tex-math ...notation="LaTeX">q </tex-math></inline-formula>-ary quantum MDS codes by using generalized Reed-Solomon (GRS) codes and Hermitian construction. The minimum distances of our quantum MDS codes can be larger than <inline-formula> <tex-math notation="LaTeX">\frac {q}{2}+1 </tex-math></inline-formula>. Three of these six classes of quantum MDS codes have longer lengths than the ones constructed in <xref ref-type="bibr" rid="ref1">1 and <xref ref-type="bibr" rid="ref2">2 , hence some of their results can be easily derived from ours via the propagation rule. Moreover, some known quantum MDS codes of specific lengths can be seen as special cases of ours and the minimum distances of some known quantum MDS codes are also improved as well.
Cyclic codes are an important class of linear codes. Bounding the minimum distance of cyclic codes is a long-standing research topic in coding theory, and several well-known and basic results have ...been developed on this topic. Recently, locally repairable codes (LRCs) have attracted much attention due to their repair efficiency in large-scale distributed storage systems. In this paper, by employing the singleton procedure technique, we first provide a sufficient condition for bounding the minimum distance of cyclic codes with typical defining sets. Secondly, by considering a specific case, we establish a connection between bounds for the minimum distance of cyclic codes and solutions to a system of inequalities. This connection leads to the derivation of new bounds, including some with general patterns. In particular, we provide three new bounds with general patterns, one of which serves as a generalization of the Betti-Sala bound. Finally, we present a generalized lower bound for a special case and construct several families of <inline-formula> <tex-math notation="LaTeX">(2, \delta) </tex-math></inline-formula>-LRCs with unbounded length and minimum distance <inline-formula> <tex-math notation="LaTeX">2\delta </tex-math></inline-formula>. It turns out that these LRCs are distance-optimal, and their parameters are new. To the best of our knowledge, this work represents the first construction of distance-optimal <inline-formula> <tex-math notation="LaTeX">(r, \delta) </tex-math></inline-formula>-LRCs with unbounded length and minimum distance exceeding <inline-formula> <tex-math notation="LaTeX">r+\delta -1 </tex-math></inline-formula>.
In this paper, we construct several classes of maximum distance separable (MDS) codes via generalized Reed-Solomon (GRS) codes and extended GRS codes, where we can determine the dimensions of their ...Euclidean hulls or Hermitian hulls. It turns out that the dimensions of Euclidean hulls or Hermitian hulls of the codes in our constructions can take all or almost all possible values. As a consequence, we can apply our results to entanglement-assisted quantum error-correcting codes (EAQECCs) and obtain several new families of MDS EAQECCs with flexible parameters. The required number of maximally entangled states of these MDS EAQECCs can take all or almost all possible values. Moreover, several new classes of q-ary MDS EAQECCs of length <inline-formula> <tex-math notation="LaTeX"> {n} > {q}+1 </tex-math></inline-formula> are also obtained.
A code is said to be an <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula>-local locally repairable code (LRC) if each of its coordinates can be repaired by accessing at most ...<inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula> other coordinates. When some of the <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula> coordinates are also erased, the <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula>-local LRC cannot accomplish the local repair, which leads to the concept of <inline-formula> <tex-math notation="LaTeX">(r,\delta) </tex-math></inline-formula>-locality. A <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary <inline-formula> <tex-math notation="LaTeX">n, k </tex-math></inline-formula> linear code <inline-formula> <tex-math notation="LaTeX">\mathcal {C} </tex-math></inline-formula> is said to have <inline-formula> <tex-math notation="LaTeX">(r, \delta) </tex-math></inline-formula>-locality (<inline-formula> <tex-math notation="LaTeX">\delta \ge 2 </tex-math></inline-formula>) if for each coordinate <inline-formula> <tex-math notation="LaTeX">i </tex-math></inline-formula>, there exists a punctured subcode of <inline-formula> <tex-math notation="LaTeX">\mathcal {C} </tex-math></inline-formula> with support containing <inline-formula> <tex-math notation="LaTeX">i </tex-math></inline-formula>, whose length is at most <inline-formula> <tex-math notation="LaTeX">r + \delta - 1 </tex-math></inline-formula>, and whose minimum distance is at least <inline-formula> <tex-math notation="LaTeX">\delta </tex-math></inline-formula>. The <inline-formula> <tex-math notation="LaTeX">(r, \delta) </tex-math></inline-formula>-LRC can tolerate <inline-formula> <tex-math notation="LaTeX">\delta -1 </tex-math></inline-formula> erasures in every local code (i.e., punctured subcode), which degenerates to an <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula>-local LRC when <inline-formula> <tex-math notation="LaTeX">\delta =2 </tex-math></inline-formula>. A <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary <inline-formula> <tex-math notation="LaTeX">(r,\delta) </tex-math></inline-formula> LRC is called optimal if it meets the singleton-like bound for <inline-formula> <tex-math notation="LaTeX">(r,\delta) </tex-math></inline-formula>-LRCs. A class of optimal <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary cyclic <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula>-local LRCs with lengths <inline-formula> <tex-math notation="LaTeX">n\mid q-1 </tex-math></inline-formula> were constructed by Tamo, Barg, Goparaju, and Calderbank based on the <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary Reed-Solomon codes. In this paper, we construct a class of optimal <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary cyclic <inline-formula> <tex-math notation="LaTeX">(r,\delta) </tex-math></inline-formula>-LRCs (<inline-formula> <tex-math notation="LaTeX">\delta \ge 2 </tex-math></inline-formula>) with length <inline-formula> <tex-math notation="LaTeX">n\mid q-1 </tex-math></inline-formula>, which generalizes the results of Tamo et al. Moreover, we construct a new class of optimal <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary cyclic <inline-formula> <tex-math notation="LaTeX">r </tex-math></inline-formula>-local LRCs with lengths <inline-formula> <tex-math notation="LaTeX">n\mid q+1 </tex-math></inline-formula> and a new class of optimal <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary cyclic <inline-formula> <tex-math notation="LaTeX">(r,\delta) </tex-math></inline-formula>-LRCs (<inline-formula> <tex-math notation="LaTeX">\delta \ge 2 </tex-math></inline-formula>) with lengths <inline-formula> <tex-math notation="LaTeX">n\mid q+1 </tex-math></inline-formula>. The constructed optimal LRCs with length <inline-formula> <tex-math notation="LaTeX">n=q+1 </tex-math></inline-formula> have the best-known length for a given finite field with size <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula> when the minimum distance is larger than 4.
Plants make use of distinct types of DNA methylation characterized by their DNA methyltransferases and modes of regulation. One type, RNA-directed DNA methylation (RdDM), is guided by small ...interfering RNAs (siRNAs) to the edges of transposons that are close to genes, areas called mCHH islands in maize (Zea mays). Another type, chromomethylation, is guided by histone H3 lysine 9 methylation to heterochromatin across the genome. We examined DNA methylation and small RNA expression in plant tissues that were mutant for both copies of the genes encoding chromomethylases as well as mutants for both copies of the genes encoding DECREASED DNA METHYLATION1 (DDM1)-type nucleosome remodelers, which facilitate chromomethylation. Both sets of double mutants were nonviable but produced embryos and endosperm. RdDM was severely compromised in the double mutant embryos, both in terms of DNA methylation and siRNAs. Loss of 24-nucleotide siRNA from mCHH islands was coupled with a gain of 21-, 22-, and 24-nucleotide siRNAs in heterochromatin. These results reveal a requirement for both chromomethylation and DDM1-type nucleosome remodeling for RdDM in mCHH islands, which we hypothesize is due to dilution of RdDM components across the genome when heterochromatin is compromised.
Bent partitions of V n (p) are quite powerful in constructing bent functions, vectorial bent functions and generalized bent functions, where V n (p) is an n -dimensional vector space over F p , n is ...an even positive integer and p is a prime. The classical examples of bent partitions are obtained from (partial) spreads. In 5, 19, two classes of bent partitions which are not obtained from (partial) spreads were presented. In 3, more bent partitions Γ 1 , Γ 2 , Γ * 1 , Γ * 2 , Θ 1 , Θ 2 were presented from (pre)semifields, including the bent partitions given in 5, 19. In this paper, we investigate the relations between bent partitions and vectorial dual-bent functions. For any prime p, we show that one can generate certain bent partitions (called bent partitions satisfying Condition C ) from certain vectorial dualbent functions (called vectorial dual-bent functions satisfying Condition A). In particular, when p is an odd prime, we show that bent partitions satisfying Condition C one-to-one correspond to vectorial dual-bent functions satisfying Condition A. We give an alternative proof that Γ 1 , Γ 2 , Γ * 1 , Γ * 2 , Θ 1 are bent partitions in terms of vectorial dual-bent functions. We present a secondary construction of vectorial dual-bent functions, which can be used to generate more bent partitions. We show that any weakly regular ternary bent function f : V n (3) → F 3 ( n is even) of 2-form can generate a bent partition. When such f is weakly regular but not regular, the generated bent partition from f is not coming from a normal bent partition, which answers an open problem proposed in 5. We give a sufficient condition on constructing partial difference sets from bent partitions, and when p is an odd prime, we provide a characterization of bent partitions satisfying Condition C in terms of partial difference sets.
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