Secondary traits other than grain yield (GY) have been successfully used to enhance the rate of genetic improvement for maize (
Zea mays L.) populations under abiotic stresses. With increasing trend ...towards the development of hybrids in the tropics there is a need to understand the genetics of these traits in inbred–hybrid breeding systems. The objectives of this study were to estimate the general combining abilities for secondary traits and their relationship with GY in a group of tropical white inbred lines and their hybrids under stress and non-stress environments. Traits were measured in inbred lines and their hybrid combinations across stress and non-stress subtropical and tropical environments in México. Hybrids showed earlier flowering, taller plants, more ears per plant (EPP), higher shelling percentage, slower leaf senescence, and higher leaf chlorophyll content than inbreds under all environments. La Posta Sequı́a (LP)-derived inbreds in general had desirable GCA for traits such as anthesis–silking interval (ASI), EPP, and leaf senescence but were more susceptible to foliar diseases. Conventionally bred maize lines had better standability, stay green, and resistance to diseases. Higher GY in lines and hybrids was associated with shorter ASI, earlier flowering, increased plant and ear height, increased EPP, increased shelling percentage, delayed senescence, and greater leaf chlorophyll concentrations. Under stress vs. non-stress conditions, we observed a higher variability for ASI and EPP, a higher inbred–hybrid correlation, and significant correlations between these traits and GY. Inbreds from LP appear to have high frequency of favorable dominant alleles for ASI and EPP.
Establishment of the best combination among heterotic groups, heterotic patterns, is crucial to the development of successful maize (Zea Mays L.) hybrids. The use of molecular markers in ...maize-breeding programs might or might not increase the efficiency of heterosis prediction by classifying diverse inbred lines into heterotic groups. The objectives of present research were to classify elite North Dakota (ND) maize inbred lines into heterotic groups and evaluate the consistency between simple sequence repeat (SSR) grouping and testcross data. Thirteen ND inbred lines representing diverse genetic background were crossed in a diallel mating design in 2000. The crosses and 12 checks were evaluated across four ND environments in 2001 and 2002. In addition, these lines were crossed to commercial inbred testers representing known heterotic groups in 2002. Hybrids between public and private lines were evaluated across three ND environments in 2003. Inbred lines representing Lancaster Sure Crop, Iowa Stiff Stalk Synthetic (BSSS), Minnesota #13, Northwestern Dent, Golden Glow pedigrees and ND inbred lines were screened with 49 SSR markers. Inbred lines ND246, ND278, ND280, ND281, ND282 and ND284 were clustered within the BSSS heterotic group. Inbreds ND277, ND285, ND286, ND290, and ND291 grouped closer to the Lancaster Sure Crop heterotic group. Inbred lines ND257 and ND288 grouped within Minnesota #13. Data from ND278 and ND290 testcrosses showed good combining ability with testers representing more than one heterotic group. Our research shows that groups of genetically similar germplasm could not be identified accurately and reliably with molecular markers even when the available germplasm was diverse contrary what has been suggested. Therefore, extensive field evaluation is recommended to classify unrelated inbred lines of maize.PUBLICATION ABSTRACT
Two ninety two hybrids developed from crossing six diversified Cytoplasmic Male Sterile (CMS) lines viz., ARG-2-1-2, ARG 6-3-1-4, MUT2-8-3-2, ARG 3, PKUZ and PRUN 29 with 40 inbred lines. Hybrids ...were evaluated for powdery mildew resistance reaction. Among 292 hybrids screened, none of the hybrids were highly resistant to powdery mildew, 33 hybrids were resistant, 37 were moderately resistant, 95 were susceptible and 126 showed highly susceptible reaction. More number of hybrids developed from PRUN 29 line was found more resistant to powdery mildew. Out of 48 hybrids developed from PRUN 29 CMS line, 15 and 16 hybrids were found to be resistant and moderately resistant reaction. Similarly 12 and 5 hybrids developed from line ARG 6-3-1-4 showed resistant and moderately resistant reaction respectively. Hybrids developed from CMS lines ARG 2-1-2 and MUT2-8-3-2 were shown susceptible reaction. Hybrids which showed sterile reaction along with resistance to powdery mildew could be further used to develop inbreds which are resistant to powdery mildew. Hybrids which showed fertile reaction along with resistance to powdery mildew will be evaluated in multilocation and multiseason to identify hybrids which are high yielding coupled with resistance to powdery mildew disease.
Present experiment was conducted at Raya, Mathura (U.P.) during the kharif season of 2008, 2009 and 2010 with four male sterile lines (female parents) and nine inbreds used as testers (male parents) ...of pearl millet in line x tester fashion. In general combining ability analysis GIB 144 found maximum g.c.a. effects for yield, stem thickness, leaf area, panicle length, panicle-girth, and 1000-grain weight, dry weight per plant and harvest index followed by ICMA 93222, GIB 3346 and ICMA 95333. None of the parents showed significant positive g.c.a. effects for number of nodes per main stem and number of leaves per main stem. In specific combining ability analysis seven crosses viz., ICMA 93222 x GIB 78, ICMA 96111 x GIB 129, ICMA 93222 x GIB 144, ICMA 93222 x GIB 129, ICMA 97333 x GIB 157, ICMA 97333 x GIB 135 and ICMA 95333 x GIB 157 were identified as the best specific combiners for yield and major yield components. Analysis of s.c.a. effects revealed that good combining parents yield better hybrids, because parents with significant positive g.c.a. effects were involved more in selected crosses than those with non-significant g.c.a. effects and negative g.c.a. effects. In the present study, the involvement of at least one good general combiner was found essential for obtaining combinations with high specific effects. Combining ability studies revealed that both general and specific combining ability variances were important but the estimates of s.c.a. variance were higher in magnitude for all the characters. Thus, indicating the predominance of non-additive gene action.
The genotoxic effects of 2 heavy metals (mercury chloride and cadmium chloride) on the gametic cells of 6
inbred lines of maize were tested in terms of cytological abnormalities. Meiosis was normal ...under control conditions.
During the treatments with mercury and cadmium there was a concentration-dependent increase in meiotic
abnormalities in all the inbred lines. A wide spectrum of chromosomal aberrations in the treated sets was stickiness,
followed by laggards, bridges, scattering, precocious movement, fragments, etc. Maximum chromosomal anomalies were
observed in inbred line CM-142 in both the treatment sets of heavy metals. Compared to CdCI_{2,} $HgCI_2$ induced more
chromosomal damage in all the inbreds. Of the 6 inbreds examined during the present investigation, CM-138 was the
most tolerant to both heavy metals, while CM-142 was the least resistant.
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A set of 21 maize inbreds were evaluated for 29 traits for studying the Distinctness, Uniformity and Stability parameters as per the guidelines issued by the Protection of Plant Varieties and ...Farmers Rights Authority (PPV&FRA), India. Out of 29 traits, five traits were monomorphic, 18 traits were dimorphic, while six traits were polymorphic. The studied quantitative traits were independent and their interaction with environment as well as themselves were negligible as revealed by modified joint regression analysis. The combine over year analysis revealed that five inbreds were completely uniform, for all the MS or MG traits, while rest of the inbreds were non-uniform for 1–4 traits, but within the acceptable limit of uniformity test as per PPV&FRA guideline. Combine over year distinct analysis revealed that all the studied inbreds were found distinct to each other except VQL 1 and CM 212, which showed non-distinctiveness to each other but showed distinctiveness to other 19 inbreds. The present data can be used to develop database for inbreds and also safeguard the ownership issue.
We investigated the effect of antisense oligodeoxynucleotides (AS ODN) against tyrosine hydroxylase (TH) on hypertension and sympathetic nervous system activity in spontaneously hypertensive rats ...(SHR). Systolic blood pressure (SBP) in SHR treated with TH AS ODN (50, 200 microg/rat, i.v.) was significantly lower than that of control SHR. Epinephrine and norepinephrine levels, TH activity, and TH protein levels in the adrenal medulla of SHR were reduced concomitant with TH AS ODN treatment-induced changes in SBP. In contrast, TH AS ODN (200 microg/rat) had no effect on SBP in Wistar-Kyoto rats (WKY), despite significantly decreased catecholamine levels, TH activity, and TH protein levels. These findings suggest that peripheral systemic injection of TH AS ODN may be effective as hypotensive therapy in SHR.
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