Physiological Regulation of Potato Tuber Dormancy

ABSTRACT

At harvest, potato (Solanum tuberosum L) tubers are dormant and will not vegetate As the period of postharvest storage is reach outed tuber dormancy is broken and shoot forth growth commences. The loss of tuber dormancy and first brunt of sprout growth is accompanied on numerous biochemical changes, many of which are detrimental to the nutritional and processing qualities of potatoes. Endogenous hormones have been propos to play a significant part in tuber dormancy regulation. The involvement of all major classes of endogenous hormones in tuber dormancy is reviewed. Based onward available evidence, it is conclud that the two ABA and ethylene are required for dormancy induction, nevertheless only ABA is needed to maintain vegetate dormancy. An increase in cytokinin sensitivity and appease appear to be the principal factors leading to the los of dormancy. Changes in endogenous IAA and GA make easy appear to be more closely related to the regulation of following sprout growth.

RESUMEN

Lo tub?©rcule de papa (Solanum tuberosum L) al momento de la cosecha se encuentran en estado latente y no tienen capacidad de germinaci??n. A medida que transcurre el periode de almacenamiento, se rompe la latencia y comienza el crecimiento del brote La supresi??n de la latencia del tub?©rculo y el inicio del crecimiento del brote son acompa?±ados por numeroso cambios bioqu?­micos, mucho de sees cuales son perjudiciales para la calidad nutricional y el procesamiento de la papa. Se se?±ala que las hormonas end??genas juegan un roi significativo en la regidaci??n de la latencia. Se hace una revisi??n sobre la forma en que intervienen las principales clases de hormonas end??genas en la latencia del tub?©rculo En base a la evidencia disponible se concluye que tanto el ABA como el etileno son requeridos para la inducci??n de la latencia, pero s??lo el ABA e necesario para mantener la latencia de la yema. Un incremento en la sensibilidad a la citoquinina y su contenido, parecen ser sees factores principales que conducen a la p?©rdida de la latencia. looks cambios en el contenido de IAA y AG parece que est??n m?? estrechamente relacionados a la regulaci??n del crecimiento ulterior del brote

Accepted for publication 6 February 2004

ADDITIONAL explanation WORDS: hormones, postharvest, Solanum tuberosum, sprouting, storage

This paper was originally neared as part of a symposium entitled "Recent Advances in the Physiology of Tuberization and Tuber Dormancy." The symposium was held forward 11 August 2003, by the Potato Association of America, in Spokane, WA.

ABBREVIATIONS: ABA, abscisic acid; B brassinosteroid; GA, gibberellin; IAA, indole-3-acetic acid; NAA, 1-naphthalene acetic acid Disclaimer: Mention of trademark or proprietary effect does not constitute a guarantee or warranty of the harvest by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other productions that may also be suitable.

INTRODUCTION

In 2001 worldwide production of potatoes surpassed 311.8 million MT (FAO est) In the same year, U production go beyonded 438 million cwt (USDA-NASS 2002) Roughly 70% of the fall potato craw is placed into medium-long-term storage to proper the demands of consumers and processors. Unlike other major forage crops, the potato is stored in a completely hydrated highly perishable form. Annual postharvest losse in the U typically amount to about 10%-15% of the harvested cut off but can be as high as 30%

Maintenance of postharvest market quality is of prime importance to farmers and processors. Tuber deterioration during storage can rise from both disease-related and physiological processe Of the physiological processe affecting postharvest tuber quality, unregulated sprouting is single of the most important. Sprouting is accompanied according to many physiological changes including increases in reducing sugar peace respiration, water loss, and glycoalkaloid ease (Burton 1989). All of these changes are detrimental to processing quality. For these reasons, the majority of potatoes placed into medium-long-term storage are treated with synthetic burst forth inhibitors. For seed growers, the situation is revers In this case, it would be desirable to rapidly break tuber dormancy to permit the sale and planting of fall-harvested potatoes in markets of the southern hemisphere. Regardless of the intended end-use, improvements in germinate control technologies are hampered by means of ignorance of the physiological bases of tuber dormancy.

In this review, the part of endogenous hormones as cognate regulators of tuber dormancy will be critically evaluated.

GENERAL DORMANCY CHARACTERISTICS

Botanically, the tuber is a highly wrap closelyed stem, and the eyes correspond to apical and lateral axillary shoot forths Tubers are vegetative over-wintering organs and like many other similar organs (seed corms, buds) exhibit varying steps of dormancy (Okubo 2000). Examples of dormancy can be set at all levels of biological complexity. Dormant organs are typically more resistant to biotic and abiotic stresse As like dormancy is considered a survival mechanism. Potato tuber dormancy is notion to begin on or about the time of tuber initiation (Burton 1989) As would be anticipateed from a developmental trait conferring a survival advantage, the inheritance pattern of tuber dormancy is tangle and QTL analyses have indicated that tuber dormancy is controll on at least nine distinct loci (Van retreat Berg et al. 1996; view Ewing, this issue), Given the genetic complexity of dormancy superintendence it is likely that the physiological processe regulating dormancy progression are equally compages Tuber dormancy can be affected by means of both preharvest and postharvest conditions. Between 3 and 25 C the fulness of tuber dormancy is inversely proportional to storage temperatures (Burton 1989) In addition to environmental outermosts tuber dormancy can be prematurely terminated at a variety of chemical treatments whose mechanisms-of-action are generally unknown. Several of these agents (i.e., gibberellic acid, bromoethane) are used to stimulate plumule growth of seed potatoes (Coleman 1987; Allen et al. 1992)