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1

Assessment of ploidy level on stress tolerance of Cenchrus species based on leaf photosynthetic characteristics

100%
Chandra A., Dubey A.
Acta Physiologiae Plantarum
|
2009
|
tom 31
|
nr 5
Many species of the genus Cenchrus, with different ploidy are important components of world grasslands. In the present investigation, influence of ploidy on leaf water potential (Ψleaf) and photosynthetic characteristics under water-stress condition was studied in 2-month-old plants of eight Cenchrus species representing three ploidy and two life spans. Stress was imposed for 2, 4, 6, and 8 days by withholding watering. Decrease in water potential, chlorophyll content, photosynthetic rate (PN), stomatal conductance for CO₂ (gs), and carboxylation efficiency (PN/Ci) occurred in all species. Nevertheless, perennial and diploid C. setigerus maintained the highest PN/Ci at maximum stress indicating its higher assimilation potential. Photosynthetic water use efficiency (PN/E) in general decreased with increase of water stress; however, at low stress, reverse trend was observed in diploid C. prieurri, C. setigerus, and tetraploid C. glaucus. Results indicate that relative reduction in photosynthetic characteristics was more in annual diploid than perennial diploid and tetraploid. Stress tolerance in terms of plant height, rolling and wilting of leaves also indicated better adaptability of tetra and hexaploid species over diploid. Moreover, recovery of different physiological traits was more pronounced in perennial tetraploid and hexaploid over annual diploid, thus making them suited more to drought conditions. Analysis of variance results showed direct correlation (r = 0.675) of ploidy with gas exchange parameters indicating better impact of this on physiological performance of different species of Cenchrus under water stress. This is the first report where influence of ploidy levels on photosynthetic characteristics and overall responses to moisture stress is studied in a tropical grass species.
2

Evaluation of genus Cenchrus based on malondialdehyde, proline content, specific leaf area and carbon isotope discrimination for drought tolerance and divergence of species at DNA level

100%
Chandra A., Dubey A.
Acta Physiologiae Plantarum
|
2008
|
tom 30
|
nr 1
Cenchrus (family Poaceae) is an important component of major grass covers of the world. Largely it is apomictic and both annual and perennial species exist in nature. Variations in contents of malondialdehyde, proline, specific leaf area and carbon isotope discrimination for drought tolerance were estimated among eight prominent species of Cenchrus. Simultaneously, genetic variations were also estimated by employing 187 RAPD primers. Of these, 23 primers did not react, 2 performed poorly and 7 produced many non-scorable bands and one primer yielded a single monomorphic band. Rest of the 154 primers generated one or more unambiguously scorable fragments. Twelve hundred and four of the 1,296 putative loci were polymorphic (93%) between at least one pair-wise comparisons among eight species. Dice coefficient and neighbor-joining algorithm analyses showed clustering patterns that fit with the known habitat of the species except perennial, C. myosuroides which formed a node between two annuals species. When these species were subjected to water stress tolerance test, a correlation (r = 0.612) between specific leaf area (SLA) and carbon isotope discrimination (CID) and difference in levels of drought tolerance based parameters among eight species were observed. Of the eight species investigated two annuals viz., C. biflorus and C. echinatus showed highest level of genetic similarity which was also evident from the similar levels of SLA, MDA, proline contents and carbon isotope discrimination values observed in these two species.
3

Change in phenylalanine ammonia lyase activity and isozyme patterns of polyphenol oxidase and peroxidase by salicylic acid lading to enhance resistance in cowpea against Rhizoctonia solani

80%
Chandra A., Saxena R., Dubey A., Saxena P.
Acta Physiologiae Plantarum
|
2007
|
tom 29
|
nr 4
In this paper, we describe a study concerning the determination of phenylalanine ammonia lyase (PAL) activities leading to decline in disease progress caused by Rhizoctonia solani after application of salicylic acid (SA). Two applications of 1.4 mM SA (pH 6.5) followed by inoculation with Rhizoctonia solani resulted in a quantitative change in polyphenol oxidase (PPO), peroxidase (PRX) isoforms and increase in PAL activities from 4.38 to 19.48 unit g⁻¹ (FM) h⁻¹ in Bundel-1, UPC-4200 and IFC-902 cowpea genotypes. Increase in PAL activities was further observed specifically in UPC-4200 when plants were exposed with Rhizoctonia solani spores. Total soluble proteins did not change after SA treatment, however they were significantly increased in SA sprayed-inoculated UPC-4200 genotype. Of the ten detected isoforms of polyphenol oxidase, isoforms 7 and 10, and isoform 4 of peroxidase showed increased activities by SA application. The disease symptoms measured as areas under progress curve (AUDPC) indicated less A value in SA sprayed Bundel-1 and UPC-4200 genotypes over their controls.
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