News from France. CIRAD Pineapple breeding program

'Smooth Cayenne' x 'Manzana' hybrids were created by the CIRAD pineapple breeding program in the nineties. Some of these hybrids have been released to farmers in the French West Indies. Flhoran 41 and Flhoran 53 proved to have solid fruit qualities for both fresh market and processing. Nevertheless, to meet needs of producers and consumers as well as to conform to new regulations regarding environment preservation and limiting the use of pesticides, pineapple breeding was relaunched at the CIRAD research centre in Martinique in 2004. This new effort will build upon one of the world's largest pineapple genebanks. The general objective is to produce new hybrids for the local and export markets. The specific objectives are to improve the storage behaviour, vigour and tolerance of pineapple hybrids to nematodes through direct hybridisation of Flhoran hybrids. A large breeding campaign begun in 2004 gave rise to more than twenty thousand hybrid seedlings issued from Flhoran hybrids. The first progenies were placed in the field in the winter of 2004-2005 and are now at the harvest stage. Despite the fact that the hybrids are not expected to express their best qualities in the first cycle, the first results are very encouraging. Most plants are highly vigorous with a strong root system and several among the very first fruits harvested have inherited the good fruit qualities of the parents. These good qualities include size, sugar and acid content, colour and firmness of the flesh, reflecting the good combining abilities of the chosen parental pairs. Selection within the progenies will be continued in 2007 and over the successive crop cycle. The best performing hybrids will be multiplied for further evaluation and selection. Meanwhile, methods for early screening for nematode tolerance and internal browning resistance will be developed. In collaboration with the Institut de recherche pour le développement (IRD), an original method has been developed to test the plant behaviour versus nematodes. Pineapple plants are grown in tubs filled with soil infested with nematodes (test) or without nematodes (control) for six months in the greenhouse. Roots and plant development and nematode infection are measured during and at the end of the assay. Tests conducted on varieties known to be susceptible or tolerant to nematodes proved the reliability of the method. We will search for nematode-tolerant hybrids among the ones selected for their general agronomic performance and fruit qualities using this newly developed method. Ongoing research also is aims at understanding the mechanisms leading to post-harvest internal browning (IB) induced by cold during fruit storage. The induction of polyphenoloxydase activities in response to cold storage is measured within leaves and fruits and correlations are searched for. A specific objective is to identify molecular probes for susceptibility to IB that could be used as an early selection tool within hybrid progenies. (Texte intégral)