The conservation and utilisation of allied gene resources is vital for the improvement of crop species. Rubber has been an undeniable beneficial commodity for the past 100 years. Progress in yield improvement over 70 years resulted in primary and hybrid clones with exceptional yielding abilities. But the extension of Hevea rubber to marginal areas necessitated breeding of new clones with resistance to environmental constraints. India, China, Brazil, Thailand, Côte d'Ivoire and Vietnam have marginal environments with single or multiple constraints like low temperature, wind, higher altitude, moisture deficit and diseases. Allied species and accessions of Brazilian Amazonian Hevea can be integrated into breeding programmes. Many of these clones are resultant of natural interspecific hybridisations. Also, allied species are excellent resources of timber. Molecular interventions revealed mt DNA of modern clones are highly conserved contributed by only two clones (PB 56 and Tjir 1). Nuclear DNA is highly divergent due to breeding and selection under varied geo-climates. The adaptation of allied species and wild accessions under a wide range of environments of Brazil promise a source of variation for breeding and selection of clones for specific marginal areas. Keywords: Allied species, gene resources, Hevea breeding, molecular diversity, marginal areas, cytoplasm, latex-timber clones, stress factors.
Priyadarshan et al. (Sun,) studied this question.
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