Performance of yam microtubers from temporary immersion system in field conditions

The yam clones ´Pacala Duclos´ and ´Belep´ of Dioscorea alata were used to evaluate the performance of microtubers formed in temporary immersion systems (TIS) in field conditions. Previously sprouted microtubers with a fresh weight higher than 3.0 gFW were used while in vitro plants and tuber crowns from conventional propagation methods served as control. In both clones there were no significant differences in qualitative morphological characters between plants from microtubers and in vitro plants for all traits but both differed significantly from plants obtained from tuber crowns. The same trend was observed for number, length, diameter and fresh weight of tubers produced 36 weeks after field planting. The number of tubers formed per plant raised from microtubers doubled that raised from tuber crowns in both clones. Microtubers from temporary immersion systems can be grown on the field and used in original seed production programs.Key words: Microtuber, yam, field, temporary immersion system

Progress in understanding Pseudocercospora banana pathogens and the development of resistant Musa germplasm

Article purchased; Published online: 9 Feb 2018Banana and plantain (Musa spp.) are important food crops in tropical and subtropical regions of the world where they generate millions of dollars annually to both subsistence farmers and exporters. Since 1902, Pseudocercospora banana pathogens, Pseudocercospora fijiensis, P. musae and P. eumusae, have emerged as major production constraints to banana and plantain. Despite concerted efforts to counter these pathogens, they have continued to negatively impact banana yield. In this review, the economic importance, distribution and the interactions between Pseudocercospora banana pathogens and Musa species are discussed. Interactions are further scrutinized in the light of an emerging climate change scenario and efforts towards the development of resistant banana germplasm are discussed. Finally, some of the opportunities and gaps in knowledge that could be exploited to further understanding of this ubiquitous pathosystem are highlighted

Effect of liquid media culture systems on yam plant growth (Dioscorea alata L. 'Pacala Duclos')

The culture system type in liquid media influences yam plant growth ('Pacala Duclos' clone). In culture systems with forced renewal of internal atmosphere in culture flasks, Temporary Immersion System (TIS) and Constant Immersion System (CIS) with aeration through continuous bubbling in culture medium, higher results were obtained in morphological and physiological plant indicators in comparison with plants obtained in culture systems with passive renewal of internal atmosphere in culture flasks or Static Liquid System (SLS). In Temporary Immersion System, the best results were obtained after six weeks of culture in relation to total length (20.8 cm), axillary bud number (8.6), fresh weight (2.1 g) and dry weight (0.18 g) per plant, as well as photosynthetic pigment content (chlorophyll a, b, and total), net photosynthesis (15.3 μmol C02.m-2.s-1), total transpiration (5.97 mmol H2O.m-2.s-1), stomatal conductance (457 μmol H2O.m-2.s-1) and leaf starch content (45.77 mg.gMF-1). Reducing sugar in culture medium with Temporary Immersion System was completely depleted, and mineral nutrients of lower contents (phosphorus, nitrogen, magnesium, calcium, iron, and manganese) in culture medium from this culture system could be related with plant growing. The results of this work could contribute to develop protocol for in vitro plant propagation of this yam clone

Efficiency of semi-automated culture systems on microtubers formation of yam (Dioscorea alata L.)

Yam clone 'Belep' in temporary immersion system showed favorable results on microtubers formation. Plants cultivated in this type of culture system were the first ones to initiate microtubers formation and produced the highest microtubers number per plant than with CIS (Constant Immersion System) and SLS (Static Liquid Medium System). These microtubers showed the greatest fresh and dry weights, as well as their diameters. In temporary immersion system, we obtained the highest total microtubers number and competent microtubers as planting material. Microtubers achieved in this type of culture system were distinguished by their quality expressed in the higher dry matter content and starch concentration. In order to carry renewals of culture media and to maintain continuous culture growing for direct planting material, knowledges on preferences and ion depletion in culture medium during microtubers formation in yam cultivated in temporary immersion system were acquired

CRISPR-Cas9-based genome editing of banana

Published online: 01 Jul 2020Genome editing is an emerging powerful new breeding tool, which can be applied for genetic improvement of banana for important agronomic traits such as resistance to biotic stresses, adaptation to climate change, and high yielding. Banana is an important staple food and cash crop, feeding millions of people in tropical and subtropical countries. Recently, CRISPR-Cas9-based genome editing system has been established for banana in a few laboratories. Here, we describe the procedures for generation of genome-edited events of banana, detection of targeted and potential off-target mutations, and phenotyping for important traits such as disease resistance. This chapter will provide readers strategy for applying CRISPR-Cas9-based genome editing for improvement of banana