A diversidade genética entre 30 genótipos indianos de batata foi analisada por meio de cariótipo, tamanho do genoma e marcadores RAPD. Análise cromossômica revelou 2n=4x=48, exceto para a cv. K. Chandramukhi (2n=4x+2=50). O tamanho e o volume cromossômico total variaram de 21,14µm no cv. K. Pukhraj a 31,91µm no cv. MS/89-60 e de 14,31µm³ no cv. MS/92-1090 a 33,16µm³ no cv. JW-160, respectivamente. O conteúdo 4C de DNA variou significativamente de 3,64 pg (~891 Mbp) no cv. MS/92-1090 a 11,12 pg (~2747 Mbp) no cv. K. Chandramukhi. Marcadores RAPD revelaram 131 bandas de DNA (300 a 2200 bp) sendo 79 delas exclusivas (7 a 71% de polimorfismo) entre os genótipos. Coeficientes de similaridade (variando de 0,29 a 0,93) e análise de cluster refletiram as tendências esperadas em relação a genótipos meios-irmãos e irmãos completos. Distâncias genéticas contempladas no dendrograma poderão auxiliar melhoristas a escolher parentais diversos para programas de melhoramento visando melhoramento varietal.

Genetic diversity in thirty Indian potatoes were analyzed employing karyotype, genome size and RAPD markers. Chromosome analysis revealed 2n = 4x = 48 except cv. K. Chandramukhi (2n = 4x + 2 = 50). Total genomic chromosome length and chromosome volume varied from 21.14µm in cv. K. Pukhraj to 31.91µm in cv. MS/89-60 and 14.31µm³ in cv. MS/92-1090 to 33.16µm³ in cv. JW-160 respectively. 4C DNA content was significantly varied from 3.640 pg (~891 Mbp) in cv. MS/92-1090 to 11.12 pg (~2747 Mbp) in cv. K. Chandramukhi. RAPD revealed 131 amplified DNA fragments (300 to 2200 bp) with 79 unique bands (7 to 71% polymorphism) among the genotypes. Similarity coefficients (ranged from 0.29 to 0.93) and cluster analysis reflected the expected trends in relationships of the full and half-sib potato genotypes. Genetic distances obtained from a dendrogram could help breeders to choose the diverse parents for a breeding program aimed at varietal improvement.

Estudiamos cuatro especies del mangle Bruguiera (Rhizophoraceae) en Orissa, India. Los cromosomas indican queB. cylindrica y B. parviflora son un grupo taxonómico, y que B. gymnorrhiza y B. sexangula son otro. Genéticamente, el par B. sexangula y B. gymnorrhiza está cercanamente emparentado con B. parviflora and B. cylindrica. Nuestros datos indican que el uso combinado de marcadores genéticos y evidencia citológica permiten discernir el polimorfismo genético interespecífico en los mangles, tanto para resolver problemas taxonómicos como para diseña estrategias eficaces de conservación.

Analysis of karyotype, nuclear DNA content and RAPD markers were performed in four species of Bruguiera (Rhizophoraceae) of Bhitarkanika mangrove forests, Orissa, India. Detailed karyotype analysis revealing 2n=34 in B. cylindrica and 2n=36 in B. gymnorrhiza was reported for the first time and 2n=34 in B. parviflora and B. sexangula was confirmed. On the basis of the common types of chromosomes present among Bruguiera, two distinct groups were found; one consists of B. cylindrica and B. parviflora and the other of B. gymnorrhiza and B. sexangula. The symmetrical karyotype with same chromosome types grouped B. cylindrica and B. parviflora together and presence of Type E chromosomes placed B. gymnorrhiza and B. sexangula in a separate group, suggesting their closer affinity in their respective group. Analysis of chromosome length, volume, INV and 4C DNA content confirmed this division. Nuclear DNA content was two-fold higher (~17.0 pg) in the second group than in the first (~8.0 pg). The amplification products generated through RAPD revealed 1-9 amplicons with size variations from 600 bp to 2 500 bp with 49.31% genetic similarity between B. gymnorrhiza and B. sexangula and 47.10% in between B. cylindrica and B. parviflora. The high copy number marker band (~ 1 100 bp) yielded in OPN-15 primer in B. parviflora the characteristic DNA marker, which was cloned and used as probes for assessment of genetic diversity, and demonstrated its close genetic affinity to B. cylindrica. B. gymnorrhiza and B. sexangula also produced similar marker bands of ~600 bp and ~2 200 bp in the same primer. All of the cytological, 4C DNA content and RAPD data confirmed the existence of two taxonomically distinct groups of Bruguiera: one consisting of B. cylindrica and B. parviflora and the other of B. gymnorrhiza and B. sexangula as placed earlier (1862) in the tribe Rhizophoreae by Bentham and Hooker, on the basis of the flowering habits of Bruguiera. Genetically, the B. sexangula and B. gymnorrhiza group was found to be very closely, rather than distantly, related to B. parviflora and B. cylindrica. Our results demonstrate that molecular markers together with cytological evidence provide an effective tool to access the existing interspecific genetic polymorphism in mangrove species, to solve the taxonomic problems and to design their conservation strategy. Rev. Biol. Trop. 55 (2): 437-448. Epub 2007 June, 29.