GERMPLASM CHARACTERIZATION OF Arachis pintoi Krap. and Greg. (LEGUMINOSAEA)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Arachis pintoi Krap. and Greg. is a herbaceous, perennial legume, exclusively native to Brazil. It is considered a multiple use legume, being grown for forage; ground cover in fruits orchards, forest, and low tillage systems; erosion control; and ornamental purposes. Although several cultivars have been released in different countries, little is known about the genetic diversity of the germplasm stored at genebanks. Our objective was to characterize and evaluate the genetic diversity of the germplasm of 35 accessions of Arachis pintoi at molecular, morphological, and agronomic levels. A. pintoi accessions were used to study the genetic diversity at the molecular level using RAPD markers. Concurrently, two tissue culture protocols were evaluated for their organogenesis ability, and capacity to generate somaclonal variation. From the original 18 primers tested, amplifications were obtained with eight, which amplified 100 polymorphic bands. Average genetic distance was estimated as 0.36, indicating that a large amount of genetic diversity exits among the accessions. The accessions were grouped by their genetic similarities into four distinct groups. Callus induction was achieved on two different Murashige and Skoog basal protocols, and shoot regeneration was achieved for several accessions on both media. Regenerated plants recovered in both protocols presented no differences in their RAPD band profile. Morphological characterization using data from stems, leaves, flowers, pegs, pods, and seeds demonstrated that the germplasm presented great morphological variability. Principal component analysis was able to discriminate the accessions in terms of three dimensions, and Cluster analysis differentiated four distinct groups. Average dry matter yield in 2003 was 4.35 Mg ha-1, and ranged from zero to 9.10 Mg ha-1. Average crude protein was 180 g kg-1 of DM and ranged from 130 to 220 g kg-1. The average value of in vitro organic matter digestion was 670 g kg-1 of DM and ranged from 600 to 730 g kg-1. Some accessions produced high seed yields reaching values above 1.00 Mg ha-1. Average seed production was 0.32 Mg ha-1 in 2003, and 0.43 Mg ha-1 in 2004. A. pintoi germplasm presented high levels of resistance to the nematode species Meloidogyne arenaria, M. javanica, and M. incognita.

ASSUNTO(S)

forage legume genetic resources tropical legume plantas forrageiras tropicais melhoramento vegetal

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