Diversity of Fungi in the Brazilian Semi-arid

Luís Fernando Pascholati Gusmão & Marcos Fabio Oliveira Marques

Fungi are one of the most divers e groups of organisms on the planet. Like other megadiverse groups, fungi are among the least known . They have an extremely important role in the environment and occur in diverse habitats, occupying different ecological niches, both in soil and water. The great majority of them are saprobes, decomposing any kind of organic matter able to be degraded, influencing and being influenced by several organisms and by physical-chemical environmental features. In a smaller number, some groups act as opportunist parasites in plants and animals; others have a symbiotic relationship with different organisms, where th e degree of dependence between the fungus and its partner varies a lot.

Considering the range of environments and the versatility on the way fungi live, there is no geographical barrier to their dist ribution; fungi can be found thriving in extreme environments that have either high or low temperature, with lack of water or in highly humid environments, besides surviving in environments extremely poor in nutrients. However, conditions of high humidity and temperature are more suitable to the establishment and growth of these organisms.

The peculiar feeding traits of these heterotrophs are reasons for its large distribution, since the versatility of these organisms is linked to their ability to produce enzymes able to degrade almost all organic substrates. The enzymatic activity, along with the capacity to produce several kinds of substances needed by different kinds of industries, such as the antagonistic substances (antibiotics, anti fungal, anti nematodes, etc.), have given fungi a biotechnological potential (see Chapter 4) not yet well explored in Brazil, moreover in the semi-arid region.

Number of Fungi on the Planet and in the Semi-arid: Current Situation

Hawksworth estimates the existence of 1.5 million specimens of fungi on the planet. Other authors, however, presume the existence of 2.7 million. Although the real number is difficult to calculate, there is the consensus among mycologists that the estimate of 1.5 million specimens is conservative. Basically, three facts explain such agreement: (i) the number of ‘orphan’ specimens (deposited in collections, but not yet named); (ii) number of species associated to insects (which is the largest group in diversity, estimated in about 3 millions species); (iii) fungi existing in geographical regions either never or little explored (tropic s and subtropics). Taking the estimate of 1.5 million of species into consideration, only 5-7% species have been described so far, since the figure for the known species is of around 80 thousand species .

Using the information from the list of municipalities in the Semi-arid published by SUDENE with literature in the area and lists of fungi deposited in herbaria and in collections of cultures in several institutions of the Northeast region, we can see that the number of fungi known for the Semi-arid is extremely low when compared to the total number of species known (see details).

However, these figures do not reflect either to the absence of fungi or in any way on the diversity of them in the Brazilian Semi-arid. There are phyla which have not been sampled yet. Being the most representative phyla worldwide, and also in the Semi-arid, the Basidiomycotas, Ascomycota and some Myxomycota which are easy to be sampled since most of them are macroscopical fungi and do not need specific techniques to be observed; the others are mostly microscopical fungi and need accurate techniques to be sampled and observed. Besides size, other features may increase such difference in numbers of fungi in the Semi-arid: (i) the geographical position of the research institutions that work with fungi (they are located in the coast , focusing their researches on the ecosystems nearby, Atlantic Forest, restinga, etc.); (ii) weather dry condition in the Semi-arid, which decreases the occurrence of fungi, although there are adapted species and; (iii) the main reason, the small number of fungi taxonomist in Brazil and therefore, the lack of human resources trained to do this kind of work.

Distribution of Fungi in the Semi-arid

Considering the numbers for fungi in different States included in the list of SUDENE, the situation is even more dramatic. In some State s like Sergipe, there are no registers of fungi and in the north of Minas Gerais, Rio Grande do Norte, Alagoas and Ceará, less than 100 species of fungi have been registered. Once again, this fact reflects the great need to form human resources. In places where there are either projects ongoing or studies concluded focusing on the diversity of fungi in the Semi-arid , the number of registers is larger, like in Pernambuco, Bahia and Piauí.

The State of Pernambuco is by far the most representative one because human resources have been trained in mycology there for decades (Chapter 25). Only recently, more attention has been given to the fungi in the State of Bahia , with the recruitment of experienced professors of mycology, which guarantees the formation and training of human resources in this area.

Distribution of fungi recorded for the Brazilian Semi-arid.

 
Number of surveyed species of fungi by State in the Brazilian Semi-arid.

Perspectives for the Study of Fungi in the Semi-arid

Results of projects on fungi diversity ongoing in the Semi-arid of Bahia have shown a surprisingly large number of new registers to Brazil and to the Semi-arid, not to mention new species; a bout 30% of collections already sampled and identified represent new registers or new species.

This current situation tends to change drastically with the efforts by PPBio of the Semi-arid (Chapter 2), which gathers groups of researchers from several institutions of the Northeast Brazil, such as UEFS, UFPE, UFRN and UFPI. The implementation of sampling protocol elaborated by most groups researching on fungi and the inclusion of more taxonomists will also increase the number of known species and a better knowledge of their geographic distribution . Meanwhile, an important step for the field will be made since this work will also result in the formation of human resources trained to identify fungi.

Cannon, P.F. 1997. Strategies for rapid assessment of fungal diversity. Biodiversity and Conservation 6: 669-680.

Hawksworth, D.L. 2001.The magnitude of fungal diversity: the 1.5 million species estimate revised. Mycological Research 105: 1422-1432.

Kirk, P.M., P.F. Cannon, J.C. David & J.A. Stalpers. 2001. Ainsworth and Bisby’s Dictionary of the Fungi. 9th Ed. CABI, Wallingford.

SUDENE, 1997. Caracterização do Semi-árido Brasileiro, avaiable on www.asabrasil.org.br.